<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      function fn1() {
        let num = 0

        return function () {
          num++
          console.log(num)
        }
      }

      fn1()()
      fn1()()
      fn1()()

      const res = fn1()
      res()
      res()
      res()
    </script>
  </body>
</html>
